The ‘Check Engine’ Light — What’s the Problem?

Posted Monday, Feb 17, 2014 by Allen B. Ury

Your dashboard’s “Check Engine” light is a mysterious thing. If often comes on when there’s no hint of engine trouble. And although it’s clearly warning you about something, it never actually tells you what the problem is. It’s as if you got an email from your doctor saying, “Call me.” Do you have cancer — or have you just forgotten to pay your most recent bill? The mind boggles.

In fact, the “Check Engine” warning can mean a lot of things, some serious, some not so. But you never know for sure until you take your car to an automotive technician with the equipment needed to translate what your car’s electronics are trying to tell you.

So you can react to your next warning with a cool head, here are the 10 most common engine problems that will make the “Check Engine” light come on:

1. Oxygen Sensor Failure — This is actually the most common part of an engine assembly to need repair or replacement. The oxygen sensor helps determine to fuel-to-air mixture, and when it goes on the fritz, it can lower your fuel efficiency by as much as 40 percent. The cost to repair an oxygen sensor, including labor, is about $300.

2. Loose Fuel Cap —Yep, failing to properly tighten you fuel cap can make the “Check Engine” light illuminate. So before you take your car to the shop, make sure the cap is on tight. If the cap needs to be replaced, it will likely just cost you a couple of bucks.

3. A Bad Catalytic Converter — Catalytic converters have been required on all U.S. cars since the 1970s. They help remove harmful pollutants from auto exhaust. Bad spark plugs or faulty ignition coils can trigger a cascade effect that causes the catalytic converter to fail. When this happens, it’s an expensive repair, usually over $1,100.

4. Bad Spark Plugs or Ignition Coils —Hopefully, your car’s sensors will detect spark plug or ignition coil failure before the catalytic converter can be damaged. If so, repairs should cost you no more than $300.

5. Failed Spark Plug Wires —Many do-it-yourselfers can replace bad spark plugs themselves. Spark plug wires? Not so easy. This operation usually requires the skills and equipment of a professional automotive technician. Together, a set of wires and plugs cost about $350 to install.

6. Malfunctioning Air Flow Sensor —This device measures the amount of air getting to your car’s engine and then directs the fuel injectors to create the appropriate air/fuel mixture. Not attending to this problem won’t make your engine fail, but it can significantly impact your fuel economy. The cost to replace a bad airflow sensor is usually about $400-$420.

7. Improperly Installed Car Alarms —This has nothing to do with your engine, but a botched after-market car alarm installation can still make your vehicle’s diagnostic systems go goofy. Fixing the mistake usually costs about $100.

8. Leaky Vacuum Hoses —Should a vacuum hose spring a leak, it will impact your engine’s Evaporative Emission Control (EVAP) system, which removes the nasty vapors produced during the internal combustion process. Replacing a vacuum hose will usually set you back about $100-$110.

9. Failing Exhaust Gas Recirculation (EGR) System — Like the catalytic converter, the EGR helps control emissions and makes your engine run more efficiently. Unlike many of the problems listed above, a bad EGR can actually impact the way your car drives, causing hesitation and misfires. EGR repairs usually run around $325.

10. Dead Battery or Charging System —When voltage starts to go, the “Check Engine” light will come on. Heat is the main culprit in killing car battery charging systems. So if problems of this sort become more common, blame global warming.

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